A practical approach to the implementation of selectivity in homonuclear multidimensional NMR with frequency selective-filtering techniques. Application to the chemical structure elucidation of complex oligosaccharides

This review describes the use of frequency-selective filters for the design of selective NMR experiments. Frequency-selective filters constitute 'user -friendly' and efficient alternatives to selective excitation in most appli cations. Different selective schemes are discussed, which are based either on selective inversion or selective refocusing of the frequencies of intere st. Selective filters can be used to transform 2D (or 3D) experiments into 1D (or 2D) analogues, or to restrict the matrix size in higher dimensional spectra. Accurate NMR parameters can be easily extracted from such spectra in short measuring times, with high digital resolution and minimum data sto rage. For these reasons, these experiments are a very useful alternative to conventional multidimensional experiments in structural and/or conformatio nal studies of small- and medium-sized molecules. Moreover, using DANTE pro cedures for selectivity, they can be easily implemented on 'routine' spectr ometers, without the need for sophisticated hardware. These methods have be en tested on a complex heterosidic compound, where they prove to afford out standing interest in achieving proton resonance assignment and chemical str ucture delineation. Copyright (C) 1999 John Wiley & Sons, Ltd.